The phenomenon of liquid metal embrittlement (LME) poses safety concerns for welded joints in themanufacturing field. In present study, LME was observed in refill friction stir spot welding (refill FSSW)of dissimilar magnesium (Mg) to galvanized steel. This marks the first reported proof of evidence ofLME in the field of solid-state welding. Microstructural characterization of cracks formed during thewelding process revealed typical characteristics of LME, specifically the penetration and enrichmentof Zn at the Mg alloy grain boundaries and the formation of a liquefied phase. Tensile tests of ZncoatedMg alloy were conducted at elevated temperatures to validate the LME phenomenon in refillFSSW and to identify the temperature range in which LME occurs. Based on these observations, amechanism of LME formation for the Mg-Zn system in refill FSSW is proposed. Additionally, strategiesto prevent LME are suggested and experimentally validated.
Chen et al. (Wed,) studied this question.